Question

Which of earths spheres is not included in the phosphorus cycle?

Answer 1

the answer is B. Atmosphere

Answer 2

The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere.

The atmosphere does not play an important role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are  solids at the symbolic ranges of temperature and pressure present on Earth.

Thus, the earths spheres like biosphere, Cryosphere  and lithosphere are included in the phosphorus cycle but atmosphere is not included in the same.